First start up the REPL by issuing this command:
clj -Sdeps '{:deps {github-mfikes/e00202b2de7cc2352fedcf92b1fe60dc {:git/url "https://gist.github.com/mfikes/e00202b2de7cc2352fedcf92b1fe60dc" :sha "68ef581813e08a92bd52e7beeea1535ab7b3337f"}}}' -m cljs.main -i @index.cljs -r
Once the REPL is waiting for the browser to connect, if it doesn't automatically, open http://localhost:9000 in your browser.
You will now be running Bocko. The following forms evaluated in the REPL will draw an American flag.